I know that when visiting the Vatican or churches that proper attire is necessary. All of the suggestions I've read emphasize that shoulders (and sometimes the head) must be covered, as well as knees -- so no shorts or short skirts. But this is rather general, IMO.

I want to know if women should wear skirts or if slacks are appropriate. Even jeans? How about for men? Obviously slacks, no shorts, but jeans for them if worn with a shirt nicer than a t-shirt? For all I know even t-shirts would be acceptable.

On Carnival's website, in looking at the shore excursions in Istanbul and Izmir, it notes that you will be requested to remove your shoes before entering mosques and to wear socks. I normally wear sandal-like shoes without socks, but if I wear such shoes will it be ok if I have knee-high hosiery on instead of actual socks??